Biết rằng $% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa8qCaeaaca % WG4bGaci4yaiaac+gacaGGZbGaaGOmaiaadIhacaWGKbGaamiEaiab % g2da9maalaaabaGaaGymaaqaaiaaisdaaaWaaeWaaeaacaWGHbGaci % 4CaiaacMgacaGGUbGaaGOmaiabgUcaRiaadkgaciGGJbGaai4Baiaa % cohacaaIYaGaey4kaSIaam4yaaGaayjkaiaawMcaaaWcbaGaaGimaa % qaaiaaigdaa0Gaey4kIipaaaa!50F5! \int\limits_0^1 {x\cos 2xdx = \frac{1}{4}\left( {a\sin 2 + b\cos 2 + c} \right)}$ với $a,b,c \in Z$ . Khẳng định nào sau đây đúng 

Đặt $% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa8qCaeaaca % WG4bGaci4yaiaac+gacaGGZbGaaGOmaiaadIhacaqGKbGaamiEaaWc % baGaaGimaaqaaiaaigdaa0Gaey4kIipaaaa!413F! I = \int\limits_0^1 {x\cos 2x{\rm{d}}x}$ . Đặt $% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbbG8FasPYRqj0-yi0dXdbba9pGe9xq-JbbG8A8frFve9 % Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaadaGabaabae % qabaGaamyDaiabg2da9iaadIhaaeaacaWGKbGaamODaiabg2da9iaa % dogacaWGVbGaam4CaiaaikdacaWG4bGaaeizaiaadIhaaaGaay5Eaa % aaaa!43D5! \left\{ \begin{array}{l} u = x\\ dv = cos2x{\rm{d}}x \end{array} \right.$$% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbbG8FasPYRqj0-yi0dXdbba9pGe9xq-JbbG8A8frFve9 % Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqGHshI3da % GabaabaeqabaGaaeizaiaadwhacqGH9aqpcaqGKbGaamiEaaqaaiaa % dAhacqGH9aqpdaWcaaqaaiaaigdaaeaacaaIYaaaaiGacohacaGGPb % GaaiOBaiaaikdacaWG4baaaiaawUhaaaaa!46BE! \Rightarrow \left\{ \begin{array}{l} {\rm{d}}u = {\rm{d}}x\\ v = \frac{1}{2}\sin 2x \end{array} \right.$

$% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbbG8FasPYRqj0-yi0dXdbba9pGe9xq-JbbG8A8frFve9 % Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqGHshI3ca % WGjbGaeyypa0ZaaqGaaeaadaWcaaqaaiaaigdaaeaacaaIYaaaaiaa % dIhaciGGZbGaaiyAaiaac6gacaaIYaGaamiEaaGaayjcSdWaa0baaS % qaaiaaicdaaeaacaaIXaaaaOGaeyOeI0YaaSaaaeaacaaIXaaabaGa % aGOmaaaadaWdXbqaaiGacohacaGGPbGaaiOBaiaaikdacaWG4bGaae % izaiaadIhaaSqaaiaaicdaaeaacaaIXaaaniabgUIiYdaaaa!51AB! \Rightarrow I = \left. {\frac{1}{2}x\sin 2x} \right|_0^1 - \frac{1}{2}\int\limits_0^1 {\sin 2x{\rm{d}}x}$ $% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbbG8FasPYRqj0-yi0dXdbba9pGe9xq-JbbG8A8frFve9 % Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqGH9aqpda % WcaaqaaiaaigdaaeaacaaIYaaaaiGacohacaGGPbGaaiOBaiaaikda % cqGHRaWkdaabcaqaamaalaaabaGaaGymaaqaaiaaisdaaaGaam4yai % aad+gacaWGZbGaaGOmaiaadIhaaiaawIa7amaaDaaaleaacaaIWaaa % baGaaGymaaaakiabg2da9maalaaabaGaaGymaaqaaiaaikdaaaGaci % 4CaiaacMgacaGGUbGaaGOmaiabgUcaRmaalaaabaGaaGymaaqaaiaa % isdaaaGaam4yaiaad+gacaWGZbGaaGOmaiabgkHiTmaalaaabaGaaG % ymaaqaaiaaisdaaaaaaa!5549! = \frac{1}{2}\sin 2 + \left. {\frac{1}{4}cos2x} \right|_0^1 = \frac{1}{2}\sin 2 + \frac{1}{4}cos2 - \frac{1}{4}$

$% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbbG8FasPYRqj0-yi0dXdbba9pGe9xq-JbbG8A8frFve9 % Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqGH9aqpda % WcaaqaaiaaigdaaeaacaaI0aaaamaabmaabaGaaGOmaiGacohacaGG % PbGaaiOBaiaaikdacqGHRaWkcaWGJbGaam4BaiaadohacaaIYaGaey % OeI0IaaGymaaGaayjkaiaawMcaaaaa!44DE! = \frac{1}{4}\left( {2\sin 2 + cos2 - 1} \right)$ $% MathType!MTEF!2!1!+- % feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbbG8FasPYRqj0-yi0dXdbba9pGe9xq-JbbG8A8frFve9 % Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqGHshI3ca % WGHbGaeyOeI0IaamOyaiabgUcaRiaadogacqGH9aqpcaaIWaaaaa!3EFD! \Rightarrow a - b + c = 0$